Polymers comprising ethylene and optionally one or more olefins are well known and have applications in a wide range of fields from film packaging to thermoplastic elastomers.
Alpha-olefin co- and homopolymers have traditionally been prepared in the presence of Ziegler-Natta catalyst systems largely based on vanadium and/or titanium and with the use of metal alkyl activators. Newer metallocene catalyst compounds have received attention due to their improved incorporation of comonomers, high activities and improvements in certain physical properties of the resultant polymers, such as puncture resistance. Although broadly described as suitable for polyolefin solution polymerization processes, metallocene catalysts have shown some limitations in their molecular weight capabilities and catalyst activity (especially at temperatures greater than about 100.degree. C. in solution processes). Due to relatively fast termination (or chain transfer) reactions, such as the beta-hydride elimination reaction, metallocene catalysts may at temperatures, typically above 100.degree. C., produce olefin polymers and copolymers having a molecular weight (Mn) of less than about 20,000. Additionally, it is generally recognized that, metallocene type catalysts in their reactive form tend to undergo deactivation processes at temperatures above about 100.degree. C.
Some of the phosphinimine Group 4 metal complexes of the present invention are not novel per se. For example, some complexes, or homologues thereof, have been disclosed in a number of scientific papers including:
Cyclopentadienyl Titanium Complexes with aryidiasenido or phosphiniminato-Ligands by J. R. Dilworth, Journal of Organometallic Chemistry, 159 (1978) 47-52; PA0 Syntheses und Reaktionen von (.eta..sup.5 -Pentamethylcyclopentadienyl)-und (.eta..sup.5 Ethyltetramethylcyclopentadienyl)titantrifluorid by S. Manshoeh et al, Chem. Ber., 1993 136, 913-919; PA0 Neue Komplexe des Titans mit silylierten Aminoiminophosphoran-und Sulfodiimidliganden by R. Hasselbring et al, Zeitschrift fur anorganische und allgemeine Chemie, 619 (1993) 1543-1550; PA0 Phosphaniminato-Komplese des Titans, Syntheses und Kristallstrukturen von CpTiCl.sub.2 (NPMe.sub.3), PA0 [TiCl.sub.3 (NPMe.sub.3)].sub.2, Ti.sub.2 Cl.sub.5 (NPMe.sub.2 Ph).sub.3 und [Ti.sub.3 Cl.sub.6 (NPMe.sub.3).sub.5 ][BPh] by T. PA0 Syntheses and reactivity of Aminobis(diorganylamino)phosphanes by G. Shick etal, Chem. Ber., 1996,129,911-917.
Rubenstahl et al, Zeitschrift fur anorganische und aligemeine Chemie, 620 (1994) 1741-1749; and
While the above art discloses some of the complexes per se, and in one instance the complex in conjunction with an activator, the art does not disclose the polymerization of olefins, and in particular the polymerization of olefins in a solution process.
A poster presentation by J. C. Stewart and D. W. Stephan, Department of Chemistry and Biochemistry, The University of Windsor, at the IDW conference at McGill University in November 1996, discloses polymerization of ethylene at room temperature using the complexes of the present invention. The turnover in terms of grams of polyethylene/mmol/hr (e.g. productivity or activity) is several orders of magnitude below that obtained with the activation of the present invention. The poster presentation does not disclose the use of the catalyst systems of the present invention at a temperature above room temperature or results which approach commercial application.
The above art does not disclose complexes of the formula: ##STR1## where Cp is a cyclopentadienyl radical, R is a C.sub.1-6 alkyl radical, and Ph is a phenyl radical which is unsubstituted or substituted by up to 6 hydrocarbyl radicals (preferably C.sub.1-6).
U.S. Pat. No. 5,625,016, issued Apr. 29, 1997, assigned to Exxon Chemical Patents Inc. discloses the polymerization of olefins and in particular the preparation of ethylene propylene rubbers or ethylene propylene diene monomer copolymers, in the presence of a catalyst system prepared from an unbridged Group 4 metal, a bulky (substituted) monocyclopentadienyl ligand, a uninegative bulky group 15 ligand and two uninegative activation reactive ligands. The disclosure of the patent teaches the group 15 ligand is an amido ligand. Additionally, all of the exemplified ligands are amido ligands. Further the disclosure teaches the group 15 ligand is disubstituted (i.e. --N--(R).sub.2). The patent does not teach a phosphinimine ligand in which the nitrogen atom is covalently bonded to the group 4 metal and also double bonded to a five valent phosphorus atom (i.e. --N.dbd.P (which is further bound at three additional coordination sites)). As such a phosphinimine ligand may be viewed as a group 15 ligand which is singly substituted. In short the reference does not teach, or suggest, the complexes of the present invention.
Catalyst systems based on bridged monocyclopentadienyl titanium compounds activated with alumoxane suitable for the preparation of ethylene-olefin copolymers of high molecular weight and high alpha-olefin content are described in U.S. Pat. No. 5,264,405. This patent teaches that the cyclopentadienyl group should be fully substituted with methyl groups and bridged to an amido group having an aliphatic or alicyclic hydrocarbyl ligand bonded through a primary, secondary or tertiary carbon. The complexes of the present invention are distinct over those of this patent as they are not bridged.